Telltale lamp socket



B. E. CARLSON TELLTALE LAMP SOCKET Feb. 15, 1949. 2,461,962

Filed Aug. 26, 1947 INVENTOR. gerzzardl" Q2/5022,

Patented Feb. 15, 1949 UNITED STATES PATENT OFFICE:

TELLTALE LAMP SOCKET Bernard E. Carlson, Chicago, 111. Application August 26, 1947, Serial No. 770,625

3 Claims.

The present invention relates to an improved and simplified telltale light socket whereby the condition of series-connected incandescent lamps or like resistance elements may be readily ascertained visually. The socket of the present invention is particularly devised for use in strings of inexpensive, series-circuit-connected ornamental Christmas tree lights.

It is an object of the invention to provide a novel and improved socket assembly in which a standard, threaded base, incandescent lamp is mounted in conjuncture with a shunt circuit including a resistor and indicating glow tube, said assembly being characterized primarily by the simplicity and inexpensiveness of production thereof.

I am aware that it has been proposed to provide hook-ups of inexpensive incandescent Xmas tree lights in which the series-connected lamp filaments are each provided with a shunt circuit including a resistor and a small neon or like glow tube connected in series with said resistor. In these arrangements, the resistance of the resistor and glow tube by-passing the small incandescent lamp is sufiiciently great that insufiicient current normally flows through the tube to illuminate the same. However, should the filament of the incandescent lamp be ruptured or burned out, the current traverses the parallel resistorglow tube circuit, causing the glow tube to illuminate and thereby visually indicate the inoperative condition of the incandescent lamp.

While indicator circuits of the foregoing type are well known, no one to my knowledge has evolved a suitably inexpensive, yet practical and effective, mechanical arrangement for incorporating the glow tube and resistor in a single unit with the provisions receiving the incandescent lamp, enabling strings of lights to be sold in competition with known types of parallel circuit hook-up. The present invention is therefore directed to, and has as its object, the provision of a practical socket assembly or arrangement for accomplishing this purpose. The assembly is only slightly more costly of production than existing series circuit units on the market and its slight additional cost isamply repaid to the user in the form of the convenience of detection of burned-out, inoperative bulbs or incandescent lamps.

The foregoing statements are indicative in a general way of the nature of the invention, but other and more specific objects will be apparent to those skilled in the art upon a full understanding of the construction and operation of the device.

A single embodiment of the invention is presented herein for purpose of exemplification, but it will be appreciated that the invention is susceptible of incorporation in other modified forms coming equally within the scope of the appended claims.

In the drawings,

Fig. 1 is a diagrammatic view illustrating the socket assembly or unit of the present invention as incorporated in a string of ornamental Xmas tree lights, eight in number;

Fig. 2 is a schematic wiring diagram illustrating the parallel circuit arrangement of each lamp of the string with a resistor and glow tube; and

Fig. 3 is an enlarged fragmentary view in longitudinal section through one of the socket assemblies illustrated in Fig. 1.

Referring to Fig. 1, there is illustrated therein a plurality of the socket assemblies In of the present invention which assemblies, like the small, standard threaded socket bases adapted to receive a well known type of inexpensive ornamental Xmas tree lights, are series-connected to one another. A conventional plug or prong connector ll receives the opposite ends of the conductor l2 connecting the assemblies l0.

Fig. 2 schematically illustrates the parallel or shunt circuit wiring of the sockets l0 and devices therein. The reference numeral l3 designates a small colored incandescent lamp of well known, ornamental type; the reference numeral I4 designates a resistor of, say, 100,000-200,000 ohms, although its value is not critical; and the reference numeral l5 designates a small 5 watt neon glow tube which is employed as an indicator. Resistor l4 and glow tube l5 are seriesconnected as a shunt across the terminals or filament leads of the incandescent lamp [3. A shunt circuit of this type is associated with each of the incandescent lamps l3 in a manner which will be appreciated.

Fig; 3 illustrates structural details of the lamp assembly ID. The same comprises a generally cylindrical base or housing l6 which may be attractively fabricated of any one of a number of well known types of plastic materials available in a large range of colors. Said housing, adjacent one end thereof, is provided with an enlarged peripheral bead I! serving to limit inward movement of a standard, small, metal lamp socket l8 which is force-fitted into the adjacent end. This socket is of a well known metal type including a threaded terminal sleeve l9 adapted to receive the threaded base of lamp l3 and a central terminal or contact point 20 insulated therefrom. An electrical circuit is completed through button 2!], terminal sleeve l9 and the filament of the incandescent lamp l3 in an entirely conventional fashion, corresponding contacts on said lamps engaging the terminals of the socket 18 when the lamp is screwed into the socket.

A lead 2! is brought in through a side aperture 22 in the wall of the cylindrical housing IE, said lead 21 and one terminal lead 23 of the thermionic glow tube being soldered to the cen'-- ter socket terminal 20. Small neon glow tubes of this type are available at a nominal cost. The

other terminal 24 of the glow tube-is connected with the resistor M. Said resistor in. turn has a lead 24 soldered to the socket sleeve terminal l9, along with the further lead 25, which is brought out through a second aperture 26 in the side wall of housing l5.

In order that the cost of production and assembly'of the component parts may be maintained at a minimum, the glow tube wand IQSiSZOl'JQ are suspended and supported in the housing- 16 solely by the relatively short connecting conductor leads 23, M, 241', the slight rigidity ofwhich is nevertheless suflicient to prevent destructive jostling and rattling internally of the housing, IS.

Said housing is enclosed at the end thereof op- V posite socket IS] with a transparent or translucent, molded plastic, dome-like cap, shield or window 21, said window havinga sleeve-portion 28 at its open end which is force-fitted into the interior of housing [6 and an'annular flange-29' which abuts the adjacent end of said housing to limit inward movement of the cap,

In use, should the filament of a lamp l3 become burned out and the-other lamps l3 also-go out, however, the circuit through resistor M and glow tube l5 of the damaged lamp becomes sufilciently energized to illuminate said glow tube and thereby visually indicate the conditionof the associated lamp i3. Otherwise, the lesser resistance of lamp is in the parallel circuit prevents illumination of the glow tube.

The assembly is characterized primarily by the simplicity and the low cost of iabricationand assembly of the component parts thereof. While the idea of shunting or by-passing' lamps in the manner illustrated in Fig. 2 is not, claimed to be inventive, nevertheless the arrangement of parts of similar circuits proposed-in'the past has:

been so complicated, impractical and costly of production as to beincapable of competing successfully with parallel circuit multiple lamp hookups. The present assembly makes possible the:

production of an inexpensive series circuit hook-z up presenting all the advantages of a parallel circuit arrangement, yet which is much less ex'- pensive, and which also is able to'compete successfully with conventional, inexpensive series circuit strings, from a price standpoint.v The cost of production of a string of lamp holders incor- 4 porating the present invention is but slightly in excess of the cost of production of the last named series circuit strings not affording the benefits herein made possible.

I claim:

1. An indicator lamp socket assembly for series-connected lamp strings comprising a hollow tubular housing having a threaded, incandescent lamp socket fixedly connected to one end thereof, said socket including electrical terminals for a filament type lamp threaded therein, a resistance circuit including an electrically energizable visual indicating device disposed in the interior'ofsaid housing and electrically connected to said terminals, whereby to be in parallel with the filament of said lamp when the latter is operably mounted in said socket, said housing having a light transmissive area adjacent said indicating device for. viewing the latter when energized, and a pair of leads extending through the side walls otsaid housing and electrically connectedito-said respective terminals.

2;: Ant indicator lamp socket assembly for series-connected lamp strings comprising a-hollowtubular housinghaving a lamp socket fixedly secured in one endthereof and provided withzcontact terminals for a lamp disposed in said socket,

electrically energizable visual indicatingmeans disposed in said housing and electrically connected to said terminals, said" housing having a light transmissive area at the end thereofopposite said socket for viewing said indicating means when energized, through" said housing and electrically connected to said respective terminals.

3. An indicator lamp socket assembly for a light transmissive window at the end thereof opposite said socket for viewing said glow tube-when the latter is energized, and conductor means ex-:

tending through said'housing betweensaid socket and window and'electrically connectedto said re spective terminals.

BERNARD E. CARLSON;

REFERENCES CITED The following references are of record in the fileof this patent:

UNITED STATES PATENTS Number Name, Date 2,021,062 Helmbright Nov. 12,1935 2,428,441 1 Waters Oct. 7,-194'1 FOREIGN PATENTS Number Country Date 12,398/1908 Great Britain June 3, 1909' and conductor means extending, 

